faq: add some faqs to documentation #10061
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faq/manage-cluster-faq.md
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| You can use [Placement Rules](/placement-rules-in-sql.md) to specify the location of data for compliance or multi-tenant applications. | ||
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| Placement Rules in SQL is designed to control the attributes of any continuous data range, such as the number of replicas, the Raft role, the placement location, abd the key ranges in which the rules take effect. |
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| Placement Rules in SQL is designed to control the attributes of any continuous data range, such as the number of replicas, the Raft role, the placement location, abd the key ranges in which the rules take effect. | |
| Placement Rules in SQL is designed to control the attributes of any continuous data range, such as the number of replicas, the Raft role, the placement location, and the key ranges in which the rules take effect. |
faq/sql-faq.md
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| @@ -7,6 +7,28 @@ summary: Learn about the FAQs related to TiDB SQL. | |||
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| This document summarizes the FAQs related to SQL operations in TiDB. | |||
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| ## Does TiDB support secondary key? | |||
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| Yes. If a column in TiDB meets all of the following conditions, it can work as a secondary key: | |||
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Better not to answer this question in this way. Secondary key is not a formal terminology, but an ability to access specific row quickly by a column other than primary key. In TiDB, we can achieve it by secondary index with not null constraint.
faq/sql-faq.md
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| For some DDL operations such as adding columns, deleting columns or dropping indexes, TiDB can perform these operations quickly. | ||
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| For some heavy DDL operations such as adding indexes, TiDB needs to backfill data, which takes a longer time (depending on the size of the table) and consumes additional resources. The impact on online traffic is tunable. TiDB can do the backfill with multiple threads, and you can tune the number of threads. |
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It's better to replace , and you can tune the number of threads with , the amount of thread is set by variables
faq/sql-faq.md
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| See [The TiDB Command Options](/command-line-flags-for-tidb-configuration.md). | |||
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| ### How to avoid hotspot issues and achieve load balancing? Is hot partition or range an issue in TiDB? | |||
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| To learn the scenarios that cause hotspots, refer to [common hotpots](/troubleshoot-hot-spot-issues.md#common-hotspots). To resolve hotspot issues, you can use the following built-in TiDB features: | |||
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The solutions of hotspot issues depends on the various causes. It's not guaranteed the given solutions resolve all problems. So we can say TiDB provides a few built-in features to resolve hotspot issues.. instead of saying the issues have to be resolved by these built-in features.
Co-authored-by: Lilian Lee <lilin@pingcap.com>
Co-authored-by: Lilian Lee <lilin@pingcap.com>
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This pull request has been accepted and is ready to merge. Commit hash: 1259ec6
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In response to a cherrypick label: new pull request created: #10149. |
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In response to a cherrypick label: new pull request created: #10150. |
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